Subband channel state information (CSI) omission for type-II CSI

ABSTRACT

Certain aspects of the present disclosure generally relate to methods and apparatus for generating and reporting CSI.

CROSS-REFERENCE TO RELATED APPLICATION & PRIORITY CLAIM

This application is a national stage application under 35 U.S.C. 371 ofPCT/CN2018/108593, filed Sep. 29, 2018, which claims the benefit of andpriority to International Patent Cooperation Treaty Application No.PCT/CN2017/105238, filed Oct. 2, 2017, which is hereby assigned to theassignee hereof and hereby expressly incorporated by reference herein asif fully set forth below and for all applicable purposes.

TECHNICAL FIELD

Certain aspects of the present disclosure generally relate to reportingof channel state information (CSI).

INTRODUCTION

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includeLong Term Evolution (LTE) systems, code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

In some examples, a wireless multiple-access communication system mayinclude a number of base stations, each simultaneously supportingcommunication for multiple communication devices, otherwise known asuser equipment (UEs). In LTE or LTE-A network, a set of one or more basestations may define an e NodeB (eNB). In other examples (e.g., in a nextgeneration or 5G network), a wireless multiple access communicationsystem may include a number of distributed units (DUs) (e.g., edge units(EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs),transmission reception points (TRPs), etc.) in communication with anumber of central units (CUs) (e.g., central nodes (CNs), access nodecontrollers (ANCs), etc.), where a set of one or more distributed units,in communication with a central unit, may define an access node (e.g., anew radio base station (NR BS), a new radio node-B (NR NB), a networknode, 5G NB, gNB, etc.). A base station or DU may communicate with a setof UEs on downlink channels (e.g., for transmissions from a base stationor to a UE) and uplink channels (e.g., for transmissions from a UE to abase station or distributed unit).

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example of an emergingtelecommunication standard is new radio (NR), for example, 5G radioaccess. NR is a set of enhancements to the LTE mobile standardpromulgated by Third Generation Partnership Project (3GPP). It isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingOFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink(UL) as well as support beamforming, multiple-input multiple-output(MIMO) antenna technology, and carrier aggregation.

Additionally, NR is expected to introduce new encoding and decodingschemes that improve transmission and reception of data. For example,Polar codes are currently being considered as a candidate forerror-correction in next-generation wireless systems such as NR. Polarcodes are a relatively recent breakthrough in coding theory, which havebeen proven to asymptotically (for code size N approaching infinity)achieve the Shannon capacity. However, while Polar codes perform well atlarge values of N, for lower values of N, polar codes suffer from poorminimum distance, leading to the development of techniques such assuccessive cancellation list (SCL) decoding, which leverage a simpleouter code having excellent minimum distance, such as a CRC orparity-check, on top of a polar inner code, such that the combined codehas excellent minimum distance.

However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in NR technology,such as improvements in encoding and decoding schemes for NR.Preferably, these improvements should be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

BRIEF SUMMARY OF SOME EMBODIMENTS

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

Certain aspects of the present disclosure provide a method of wirelesscommunication, according to certain aspects of the present disclosure.The method generally includes determining, in a two-part channel stateinformation (CSI) reporting scheme, a first number M out of N subbandsto use for feeding back CSI in a second CSI feedback part, wherein Nrepresents a configured number of supported subbands for subbandprecoding matrix indicator (PMI) reporting, deciding, based on a rankindicator (RI) and a non-zero wideband amplitude (NZWA) per layer, whichof the N subbands to omit from the M subbands, and reporting CSIfeedback for the M subbands in the second CS feedback part.

The techniques may be embodied in methods, apparatuses, and computerprogram products. Other aspects, features, and embodiments of thepresent invention will become apparent to those of ordinary skill in theart, upon reviewing the following description of specific, exemplaryembodiments of the present invention in conjunction with theaccompanying figures. While features of the present invention may bediscussed relative to certain embodiments and figures below, allembodiments of the present invention can include one or more of theadvantageous features discussed herein. In other words, while one ormore embodiments may be discussed as having certain advantageousfeatures, one or more of such features may also be used in accordancewith the various embodiments of the invention discussed herein. Insimilar fashion, while exemplary embodiments may be discussed below asdevice, system, or method embodiments it should be understood that suchexemplary embodiments can be implemented in various devices, systems,and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 is a block diagram conceptually illustrating an exampletelecommunications system, in accordance with certain aspects of thepresent disclosure.

FIG. 2 is a block diagram illustrating an example logical architectureof a distributed RAN, in accordance with certain aspects of the presentdisclosure.

FIG. 3 is a diagram illustrating an example physical architecture of adistributed RAN, in accordance with certain aspects of the presentdisclosure.

FIG. 4 is a block diagram conceptually illustrating a design of anexample BS and user equipment (UE), in accordance with certain aspectsof the present disclosure.

FIG. 5 is a diagram showing examples for implementing a communicationprotocol stack, in accordance with certain aspects of the presentdisclosure.

FIG. 6 illustrates a block diagram of an example wireless device inaccordance with certain aspects of the present disclosure.

FIG. 7 illustrates an example of a DL-centric subframe, in accordancewith certain aspects of the present disclosure.

FIG. 8 illustrates an example of an UL-centric subframe, in accordancewith certain aspects of the present disclosure.

FIG. 9 illustrates example operations for wireless communications, inaccordance with certain aspects of the present disclosure.

FIG. 10 illustrates an example table that may be used to determine anumber of subbands for CSI reporting, in accordance with certain aspectsof the present disclosure.

FIG. 11 illustrates an example of CQI associated subbands selected by adecimation pattern, in accordance with certain aspects of the presentdisclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processingsystems, and computer readable mediums for encoding bits of information.Such encoding can be used, for example, for compression or storage, orfor transmission in networks, including wireless networks. For example,such encoding may be adopted for new radio (NR) (new radio accesstechnology or 5G technology) wireless communication systems. It shouldbe understood that, while aspects of the present disclosure are proposedin relation to a wireless communication system, the techniques presentedherein are not limited to such wireless communication system. Forexample, the techniques presented herein may equally apply tocompression or storage, or to other communication systems such as fibercommunication systems, hard-wire copper communication systems, and thelike. In other words, the techniques presented herein may be applied toany system using an encoder.

NR may support various wireless communication services, such as Enhancedmobile broadband (eMBB) targeting wide bandwidth (e.g. 80 MHz beyond),millimeter wave (mmW) targeting high carrier frequency (e.g. 27 GHz orbeyond), massive MTC (mMTC) targeting non-backward compatible MTCtechniques, and/or mission critical targeting ultra reliable low latencycommunications (URLLC). These services may include latency andreliability requirements. These services may also have differenttransmission time intervals (TTI) to meet respective quality of service(QoS) requirements. In addition, these services may co-exist in the samesubframe.

Example Wireless Communications System

The techniques described herein may be used for various wirelesscommunication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asuniversal terrestrial radio access (UTRA), cdma2000, etc. UTRA includeswideband CDMA (WCDMA), time division synchronous CDMA (TD-SCDMA), andother variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856standards. A TDMA network may implement a radio technology such asglobal system for mobile communications (GSM). An OFDMA network mayimplement a radio technology such as evolved UTRA (E-UTRA), ultra mobilebroadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDM®, etc. UTRA and E-UTRA are part of universal mobiletelecommunication system (UMTS). 3GPP Long Term Evolution (LTE) andLTE-Advanced (LTE-A), in both frequency division duplex (FDD) and timedivision duplex (TDD), are new releases of UMTS that use E-UTRA, whichemploys OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA,UMTS, LTE, LTE-A and GSM are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB aredescribed in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). The techniques described herein may beused for the wireless networks and radio technologies Additionally, thetechniques presented herein may be used in various other non-wirelesscommunication networks, such as fiber network, hard-wire “copper”networks, and the like, or in digital storage or compression. In otherwords, the techniques presented herein may be used in any system whichincludes an encoder.

FIG. 1 illustrates an example wireless network 100, such as a new radio(NR) or 5G network, in which aspects of the present disclosure may beperformed, for example, for reducing the search space ofmaximum-likelihood (ML) decoding for polar codes. In some cases, thenetwork 100 may be a fiber network, a hard-wire “copper” network, or thelike.

As illustrated in FIG. 1, the wireless network 100 may include a numberof BSs 110 and other network entities. A BS may be a station thatcommunicates with UEs. Each BS 110 may provide communication coveragefor a particular geographic area. In 3GPP, the term “cell” can refer toa coverage area of a Node B and/or a Node B subsystem serving thiscoverage area, depending on the context in which the term is used. In NRsystems, the term “cell” and eNB, Node B, 5G NB, AP, NR BS, NR BS, BS,or TRP may be interchangeable. In some examples, a cell may notnecessarily be stationary, and the geographic area of the cell may moveaccording to the location of a mobile base station. In some examples,the base stations may be interconnected to one another and/or to one ormore other base stations or network nodes (not shown) in the wirelessnetwork 100 through various types of backhaul interfaces such as adirect physical connection, a virtual network, or the like using anysuitable transport network.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular radioaccess technology (RAT) and may operate on one or more frequencies. ARAT may also be referred to as a radio technology, an air interface,etc. A frequency may also be referred to as a carrier, a frequencychannel, etc. Each frequency may support a single RAT in a givengeographic area in order to avoid interference between wireless networksof different RATs. In some cases, NR or 5G RAT networks may be deployed,employing a multi-slice network architecture.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or other types of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a Closed Subscriber Group (CSG), UEs for users in the home,etc.). A BS for a macro cell may be referred to as a macro BS. A BS fora pico cell may be referred to as a pico BS. A BS for a femto cell maybe referred to as a femto BS or a home BS. In the example shown in FIG.1, the BSs 110 a, 110 b and 110 c may be macro BSs for the macro cells102 a, 102 b and 102 c, respectively. The BS 110 x may be a pico BS fora pico cell 102 x. The BSs 110 y and 110 z may be femto BS for the femtocells 102 y and 102 z, respectively. A BS may support one or multiple(e.g., three) cells.

The wireless network 100 may also include relay stations. A relaystation is a station that receives a transmission of data and/or otherinformation from an upstream station (e.g., a BS or a UE) and sends atransmission of the data and/or other information to a downstreamstation (e.g., a UE or a BS). A relay station may also be a UE thatrelays transmissions for other UEs. In the example shown in FIG. 1, arelay station 110 r may communicate with the BS 110 a and a UE 120 r inorder to facilitate communication between the BS 110 a and the UE 120 r.A relay station may also be referred to as a relay BS, a relay, etc.

The wireless network 100 may be a heterogeneous network that includesBSs of different types, e.g., macro BS, pico BS, femto BS, relays, etc.These different types of BSs may have different transmit power levels,different coverage areas, and different impact on interference in thewireless network 100. For example, macro BS may have a high transmitpower level (e.g., 20 Watts) whereas pico BS, femto BS, and relays mayhave a lower transmit power level (e.g., 1 Watt).

The wireless network 100 may support synchronous or asynchronousoperation. For synchronous operation, the BSs may have similar frametiming, and transmissions from different BSs may be approximatelyaligned in time. For asynchronous operation, the BSs may have differentframe timing, and transmissions from different BSs may not be aligned intime. The techniques described herein may be used for both synchronousand asynchronous operation.

A network controller 130 may couple to a set of BSs and providecoordination and control for these BSs. The network controller 130 maycommunicate with the BSs 110 via a backhaul. The BSs 110 may alsocommunicate with one another, e.g., directly or indirectly via wirelessor wireline backhaul.

The UEs 120 (e.g., 120 x, 120 y, etc.) may be dispersed throughout thewireless network 100, and each UE may be stationary or mobile. A UE mayalso be referred to as a mobile station, a terminal, an access terminal,a subscriber unit, a station, a Customer Premises Equipment (CPE), acellular phone, a smart phone, a personal digital assistant (PDA), awireless modem, a wireless communications device, a handheld device, alaptop computer, a cordless phone, a wireless local loop (WLL) station,a tablet, a camera, a gaming device, a netbook, a smartbook, anultrabook, a medical device or medical equipment, a biometricsensor/device, a wearable device such as a smart watch, smart clothing,smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, asmart bracelet, etc.), an entertainment device (e.g., a music device, avideo device, a satellite radio, etc.), a vehicular component or sensor,a smart meter/sensor, industrial manufacturing equipment, a globalpositioning system device, or any other suitable device that isconfigured to communicate via a wireless or wired medium. Some UEs maybe considered evolved or machine-type communication (MTC) devices orevolved MTC (eMTC) devices. MTC and eMTC UEs include, for example,robots, drones, remote devices, sensors, meters, monitors, locationtags, etc., that may communicate with a BS, another device (e.g., remotedevice), or some other entity. A wireless node may provide, for example,connectivity for or to a network (e.g., a wide area network such asInternet or a cellular network) via a wired or wireless communicationlink. Some UEs may be considered Internet-of-Things (IoT) devices.

In FIG. 1, a solid line with double arrows indicates desiredtransmissions between a UE and a serving BS, which is a BS designated toserve the UE on the downlink and/or uplink. A dashed line with doublearrows indicates interfering transmissions between a UE and a BS.

Certain wireless networks (e.g., LTE) utilize orthogonal frequencydivision multiplexing (OFDM) on the downlink and single-carrierfrequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDMpartition the system bandwidth into multiple (K) orthogonal subcarriers,which are also commonly referred to as tones, bins, etc. Each subcarriermay be modulated with data. In general, modulation symbols are sent inthe frequency domain with OFDM and in the time domain with SC-FDM. Thespacing between adjacent subcarriers may be fixed, and the total numberof subcarriers (K) may be dependent on the system bandwidth. Forexample, the spacing of the subcarriers may be 15 kHz and the minimumresource allocation (called a ‘resource block’) may be 12 subcarriers(or 180 kHz). Consequently, the nominal FFT size may be equal to 128,256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10 or 20megahertz (MHz), respectively. The system bandwidth may also bepartitioned into subbands. For example, a subband may cover 1.08 MHz(i.e., 6 resource blocks), and there may be 1, 2, 4, 8 or 16 subbandsfor system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated withLTE technologies, aspects of the present disclosure may be applicablewith other wireless communications systems, such as NR/S5G.

NR may utilize OFDM with a CP on the uplink and downlink and includesupport for half-duplex operation using TDD. A single component carrierbandwidth of 100 MHz may be supported. NR resource blocks may span 12sub-carriers with a subcarrier bandwidth of 75 kHz over a 0.1 msduration. Each radio frame has a length of 10 ms and may consist of twohalf frames, each half frame comprising five subframes each with alength of 1 ms. Each subframe may indicate a link direction (i.e., DL orUL) for data transmission and the link direction for each subframe maybe dynamically switched. Each subframe may include DL/UL data as well asDL/UL control data. UL and DL subframes for NR may be as described inmore detail below with respect to FIGS. 6 and 7. Beamforming may besupported and beam direction may be dynamically configured. MIMOtransmissions with preceding may also be supported. MIMO configurationsin the DL may support up to 8 transmit antennas with multi-layer DLtransmissions up to 8 streams and up to 2 streams per UE. Multi-layertransmissions with up to 2 streams per UE may be supported. Aggregationof multiple cells may be supported with up to 8 serving cells.Alternatively, NR may support a different air interface, other than anOFDM-based. NR networks may include entities such CUs and/or DUs.

In some examples, access to the air interface may be scheduled, whereina scheduling entity (e.g., a base station) allocates resources forcommunication among some or all devices and equipment within its servicearea or cell. Within the present disclosure, as discussed further below,the scheduling entity may be responsible for scheduling, assigning,reconfiguring, and releasing resources for one or more subordinateentities. That is, for scheduled communication, subordinate entitiesutilize resources allocated by the scheduling entity. Base stations arenot the only entities that may function as a scheduling entity. That is,in some examples, a UE may function as a scheduling entity, schedulingresources for one or more subordinate entities (e.g., one or more otherUEs). In this example, the UE is functioning as a scheduling entity, andother UEs utilize resources scheduled by the UE for wirelesscommunication. A UE may function as a scheduling entity in apeer-to-peer (P2P) network, and/or in a mesh network. In a mesh networkexample, UEs may optionally communicate directly with one another inaddition to communicating with the scheduling entity.

Thus, in a wireless communication network with a scheduled access totime-frequency resources and having a cellular configuration, a P2Pconfiguration, and a mesh configuration, a scheduling entity and one ormore subordinate entities may communicate utilizing the scheduledresources.

As noted above, a RAN may include a CU and DUs. A NR BS (e.g., gNB, 5GNode B, Node B, transmission reception point (TRP), access point (AP))may correspond to one or multiple BSs. NR cells can be configured asaccess cell (ACells) or data only cells (DCells). For example, the RAN(e.g., a central unit or distributed unit) can configure the cells.DCells may be cells used for carrier aggregation or dual connectivity,but not used for initial access, cell selection/reselection, orhandover. In some cases DCells may not transmit synchronizationsignals—in some case cases DCells may transmit SS. NR BSs may transmitdownlink signals to UEs indicating the cell type. Based on the cell typeindication, the UE may communicate with the NR BS. For example, the UEmay determine NR BSs to consider for cell selection, access, handover,and/or measurement based on the indicated cell type.

FIG. 2 illustrates an example logical architecture of a distributedradio access network (RAN) 200, which may be implemented in the wirelesscommunication system illustrated in FIG. 1. A 5G access node 206 mayinclude an access node controller (ANC) 202. The ANC may be a centralunit (CU) of the distributed RAN 200. The backhaul interface to the nextgeneration core network (NG-CN) 204 may terminate at the ANC. Thebackhaul interface to neighboring next generation access nodes (NG-ANs)may terminate at the ANC. The ANC may include one or more TRPs 208(which may also be referred to as BSs, NR BSs, Node Bs, 5G NBs, APs, orsome other term). As described above, a TRP may be used interchangeablywith “cell.”

The TRPs 208 may be a DU. The TRPs may be connected to one ANC (ANC 202)or more than one ANC (not illustrated). For example, for RAN sharing,radio as a service (RaaS), and service specific AND deployments, the TRPmay be connected to more than one ANC. A TRP may include one or moreantenna ports. The TRPs may be configured to individually (e.g., dynamicselection) or jointly (e.g., joint transmission) serve traffic to a UE.

The local architecture 200 may be used to illustrate fronthauldefinition. The architecture may be defined that support fronthaulingsolutions across different deployment types. For example, thearchitecture may be based on transmit network capabilities (e.g.,bandwidth, latency, and/or jitter).

The architecture may share features and/or components with LTE.According to aspects, the next generation AN (NG-AN) 210 may supportdual connectivity with NR The NG-AN may share a common fronthaul for LTEand NR.

The architecture may enable cooperation between and among TRPs 208. Forexample, cooperation may be preset within a TRP and/or across TRPs viathe ANC 202. According to aspects, no inter-TRP interface may beneeded/present.

According to aspects, a dynamic configuration of split logical functionsmay be present within the architecture 200. As will be described in moredetail with reference to FIG. 5, the Radio Resource Control (RRC) layer,Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC)layer, Medium Access Control (MAC) layer, and a Physical (PHY) layersmay be adaptably placed at the DU or CU (e.g., TRP or ANC,respectively). According to certain aspects, a BS may include a centralunit (CU) (e.g., ANC 202) and/or one or more distributed units (e.g.,one or more TRPs 208).

FIG. 3 illustrates an example physical architecture of a distributed RAN300, according to aspects of the present disclosure. A centralized corenetwork unit (C-CU) 302 may host core network functions. The C-CU may becentrally deployed. C-CU functionality may be offloaded (e.g., toadvanced wireless services (AWS)), in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 304 may host one or more ANC functions.Optionally, the C-RU may host core network functions locally. The C-RUmay have distributed deployment. The C-RU may be closer to the networkedge.

A DU 306 may host one or more TRPs (edge node (EN), an edge unit (EU), aradio head (RH), a smart radio head (SRH), or the like). The DU may belocated at edges of the network with radio frequency (RF) functionality.

FIG. 4 illustrates example components of the BS 110 and UE 120illustrated in FIG. 1, which may be used to implement aspects of thepresent disclosure. As described above, the BS may include a TRP. One ormore components of the BS 110 and UE 120 may be used to practice aspectsof the present disclosure. For example, antennas 452, Tx/Rx 222,processors 466, 458, 464, and/or controller/processor 480 of the UE 120and/or antennas 434, processors 460, 420, 438, and/orcontroller/processor 440 of the BS 110 may be used to perform theoperations described herein and illustrated with reference to FIG. 9.

According to aspects, for a restricted association scenario, the basestation 110 may be the macro BS 110 c in FIG. 1, and the UE 120 may bethe UE 120 y. The base station 110 may also be a base station of someother type. The base station 110 may be equipped with antennas 434 athrough 434 t, and the UE 120 may be equipped with antennas 452 athrough 452 r.

At the base station 110, a transmit processor 420 may receive data froma data source 412 and control information from a controller/processor440. The control information may be for the Physical Broadcast Channel(PBCH), Physical Control Format Indicator Channel (PCFICH), PhysicalHybrid ARQ Indicator Channel (PHICH), Physical Downlink Control Channel(PDCCH), etc. The data may be for the Physical Downlink Shared Channel(PDSCH), etc. The processor 420 may process (e.g., encode and symbolmap) the data and control information to obtain data symbols and controlsymbols, respectively. The processor 420 may also generate referencesymbols, e.g., for the PSS, SSS, and cell-specific reference signal. Atransmit (TX) multiple-input multiple-output (MIMO) processor 430 mayperform spatial processing (e.g., precoding) on the data symbols, thecontrol symbols, and/or the reference symbols, if applicable, and mayprovide output symbol streams to the modulators (MODs) 432 a through 432t. Each modulator 432 may process a respective output symbol stream(e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator432 may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal.Downlink signals from modulators 432 a through 432 t may be transmittedvia the antennas 434 a through 434 t, respectively.

At the UE 120, the antennas 452 a through 452 r may receive the downlinksignals from the base station 110 and may provide received signals tothe demodulators (DEMODs) 454 a through 454 r, respectively. Eachdemodulator 454 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 454 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 456 may obtainreceived symbols from all the demodulators 454 a through 454 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 458 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded data forthe UE 120 to a data sink 460, and provide decoded control informationto a controller/processor 480.

On the uplink, at the UE 120, a transmit processor 464 may receive andprocess data (e.g., for the Physical Uplink Shared Channel (PUSCH)) froma data source 462 and control information (e.g., for the Physical UplinkControl Channel (PUCCH) from the controller/processor 480. The transmitprocessor 464 may also generate reference symbols for a referencesignal. The symbols from the transmit processor 464 may be precoded by aTX MIMO processor 466 if applicable, further processed by thedemodulators 454 a through 454 r (e.g., for SC-FDM, etc.), andtransmitted to the base station 110. At the BS 110, the uplink signalsfrom the UE 120 may be received by the antennas 434, processed by themodulators 432, detected by a MIMO detector 436 if applicable, andfurther processed by a receive processor 438 to obtain decoded data andcontrol information sent by the UE 120. The receive processor 438 mayprovide the decoded data to a data sink 439 and the decoded controlinformation to the controller/processor 440.

The controllers/processors 440 and 480 may direct the operation at thebase station 110 and the UE 120, respectively. The processor 440 and/orother processors and modules at the base station 110 may perform ordirect, e.g., the execution of the functional blocks illustrated in FIG.6, and/or other processes for the techniques described herein. Theprocessor 480 and/or other processors and modules at the UE 120 may alsoperform or direct, e.g., the execution of the functional blocksillustrated in FIG. 7, and/or other processes for the techniquesdescribed herein. The memories 442 and 482 may store data and programcodes for the BS 110 and the UE 120, respectively. A scheduler 444 mayschedule UEs for data transmission on the downlink and/or uplink.

FIG. 5 illustrates a diagram 500 showing examples for implementing acommunications protocol stack, according to aspects of the presentdisclosure. The illustrated communications protocol stacks may beimplemented by devices operating in a in a 5G system (e.g., a systemthat supports uplink-based mobility). Diagram 500 illustrates acommunications protocol stack including a Radio Resource Control (RRC)layer 510, a Packet Data Convergence Protocol (PDCP) layer 515, a RadioLink Control (RLC) layer 520, a Medium Access Control (MAC) layer 525,and a Physical (PHY) layer 530. In various examples the layers of aprotocol stack may be implemented as separate modules of software,portions of a processor or ASIC, portions of non-collocated devicesconnected by a communications link, or various combinations thereof.Collocated and non-collocated implementations may be used, for example,in a protocol stack for a network access device (e.g., ANs, CUs, and/orDUs) or a UE.

A first option 505-a shows a split implementation of a protocol stack,in which implementation of the protocol stack is split between acentralized network access device (e.g., an ANC 202 in FIG. 2) anddistributed network access device (e.g., DU 208 in FIG. 2). In the firstoption 505-a, an RRC layer 510 and a PDCP layer 515 may be implementedby the central unit, and an RLC layer 520, a MAC layer 525, and a PHYlayer 530 may be implemented by the DU. In various examples the CU andthe DU may be collocated or non-collocated. The first option 505-a maybe useful in a macro cell, micro cell, or pico cell deployment.

A second option 505-b shows a unified implementation of a protocolstack, in which the protocol stack is implemented in a single networkaccess device (e.g., access node (AN), new radio base station (NR BS), anew radio Node-B (NR NB), a network node (NN), or the like). In thesecond option, the RRC layer 510, the PDCP layer 515, the RLC layer 520,the MAC layer 525, and the PHY layer 530 may each be implemented by theAN. The second option 505-b may be useful in a femto cell deployment.

Regardless of whether a network access device implements part or all ofa protocol stack, a UE may implement an entire protocol stack (e.g., theRRC layer 510, the PDCP layer 515, the RLC layer 520, the MAC layer 525,and the PHY layer 530).

FIG. 6 illustrates various components that may be utilized in a wirelesscommunications device 602 that may be employed within the wirelesscommunication system from FIG. 1. The wireless communications device 602is an example of a device that may be configured to implement thevarious methods described herein, for example, for reducing the searchspace of ML decoding for polar codes. The wireless communications device602 may be an BS 110 from FIG. 1 or any of user equipments 120.

The wireless communications device 602 may include a processor 604 whichcontrols operation of the wireless communications device 602. Theprocessor 604 may also be referred to as a central processing unit(CPU). Memory 606, which may include both read-only memory (ROM) andrandom access memory (RAM), provides instructions and data to theprocessor 604. A portion of the memory 606 may also include non-volatilerandom access memory (NVRAM). The processor 604 typically performslogical and arithmetic operations based on program instructions storedwithin the memory 606. The instructions in the memory 606 may beexecutable to implement the methods described herein.

The wireless communications device 602 may also include a housing 608that may include a transmitter 610 and a receiver 612 to allowtransmission and reception of data between the wireless communicationsdevice 602 and a remote location. The transmitter 610 and receiver 612may be combined into a transceiver 614. A single or a plurality oftransmit antennas 616 may be attached to the housing 608 andelectrically coupled to the transceiver 614. The wireless communicationsdevice 602 may also include (not shown) multiple transmitters, multiplereceivers, and multiple transceivers.

The wireless communications device 602 may also include a signaldetector 618 that may be used in an effort to detect and quantify thelevel of signals received by the transceiver 614. The signal detector618 may detect such signals as total energy, energy per subcarrier persymbol, power spectral density and other signals. The wirelesscommunications device 602 may also include a digital signal processor(DSP) 620 for use in processing signals.

Additionally, the wireless communications device 602 may also include anencoder 622 for use in encoding signals for transmission. For example,in some cases, the encoder 622 may be configured to distribute/assign afirst one or more bits into a location of an information stream, whereinthe first one or more bits indicate at least one of a bit value of oneor more second bits in the information stream or a size of theinformation stream.

Further, the wireless communications device 602 may include a decoder624 for use in decoding received signals encoded using techniquespresented herein. For example, in some cases, the decoder 624 may beconfigured to decode a first portion of a codeword, wherein the firstportion of the codeword corresponds to a location in the informationstream where a first one or more bits are assigned, wherein the firstone or more bits indicate at least one of bit value of one or moresecond bits in the information stream or a size of the informationstream, determine the bit value of the one or more second bits based, atleast in part, on the first one or more bits, and decode a remainingportion of the codeword based on the determined bit value of the one ormore second bits.

The various components of the wireless communications device 602 may becoupled together by a bus system 626, which may include a power bus, acontrol signal bus, and a status signal bus in addition to a data bus.The processor 604 may be configured to access instructions stored in thememory 606 to perform connectionless access, in accordance with aspectsof the present disclosure discussed below.

FIG. 7 is a diagram 700 showing an example of a DL-centric subframe,which may be used by one or more devices (e.g., BS 110 and/or UE 120) tocommunicate in the wireless network 100. The DL-centric subframe mayinclude a control portion 702. The control portion 702 may exist in theinitial or beginning portion of the DL-centric subframe. The controlportion 702 may include various scheduling information and/or controlinformation corresponding to various portions of the DL-centricsubframe. In some configurations, the control portion 702 may be aphysical DL control channel (PDCCH), as indicated in FIG. 7. TheDL-centric subframe may also include a DL data portion 704. The DL dataportion 704 may sometimes be referred to as the payload of theDL-centric subframe. The DL data portion 704 may include thecommunication resources utilized to communicate DL data from thescheduling entity (e.g., UE or BS) to the subordinate entity (e.g., UE).In some configurations, the DL data portion 704 may be a physical DLshared channel (PDSCH).

The DL-centric subframe may also include a common UL portion 706. Thecommon UL portion 706 may sometimes be referred to as an UL burst, acommon UL burst, and/or various other suitable terms. The common ULportion 706 may include feedback information corresponding to variousother portions of the DL-centric subframe. For example, the common ULportion 706 may include feedback information corresponding to thecontrol portion 702. Non-limiting examples of feedback information mayinclude an ACK signal, a NACK signal, a HARQ indicator, and/or variousother suitable types of information. The common UL portion 706 mayinclude additional or alternative information, such as informationpertaining to random access channel (RACH) procedures, schedulingrequests (SRs), and various other suitable types of information. Asillustrated in FIG. 7, the end of the DL data portion 704 may beseparated in time from the beginning of the common UL portion 706. Thistime separation may sometimes be referred to as a gap, a guard period, aguard interval, and/or various other suitable terms. This separationprovides time for the switch-over from DL communication (e.g., receptionoperation by the subordinate entity (e.g., UE)) to UL communication(e.g., transmission by the subordinate entity (e.g., UE)). One ofordinary skill in the art will understand that the foregoing is merelyone example of a DL-centric subframe and alternative structures havingsimilar features may exist without necessarily deviating from theaspects described herein.

FIG. 8 is a diagram 800 showing an example of an UL-centric subframe,which may be used by one or more devices (e.g., BS 110 and/or UE 120) tocommunicate in the wireless network 100. The UL-centric subframe mayinclude a control portion 802. The control portion 802 may exist in theinitial or beginning portion of the UL-centric subframe. The controlportion 802 in FIG. 8 may be similar to the control portion describedabove with reference to FIG. 7. The UL-centric subframe may also includean UL data portion 804. The UL data portion 804 may sometimes bereferred to as the payload of the UL-centric subframe. The UL portionmay refer to the communication resources utilized to communicate UL datafrom the subordinate entity (e.g., UE) to the scheduling entity (e.g.,UE or BS). In some configurations, the control portion 802 may be aphysical DL control channel (PDCCH).

As illustrated in FIG. 8, the end of the control portion 802 may beseparated in time from the beginning of the UL data portion 804. Thistime separation may sometimes be referred to as a gap, guard period,guard interval, and/or various other suitable terms. This separationprovides time for the switch-over from DL communication (e.g., receptionoperation by the scheduling entity) to UL communication (e.g.,transmission by the scheduling entity). The UL-centric subframe may alsoinclude a common UL portion 806. The common UL portion 806 in FIG. 8 maybe similar to the common UL portion 806 described above with referenceto FIG. 8. The common UL portion 806 may additional or alternativeinclude information pertaining to channel quality indicator (CQI),sounding reference signals (SRSs), and various other suitable types ofinformation. One of ordinary skill in the art will understand that theforegoing is merely one example of an UL-centric subframe andalternative structures having similar features may exist withoutnecessarily deviating from the aspects described herein.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V)communications, Internet of Everything (IoE) communications, IoTcommunications, mission-critical mesh, and/or various other suitableapplications. Generally, a sidelink signal may refer to a signalcommunicated from one subordinate entity (e.g., UE1) to anothersubordinate entity (e.g., UE2) without relaying that communicationthrough the scheduling entity (e.g., UE or BS), even though thescheduling entity may be utilized for scheduling and/or controlpurposes. In some examples, the sidelink signals may be communicatedusing a licensed spectrum (unlike wireless local area networks, whichtypically use an unlicensed spectrum).

A UE may operate in various radio resource configurations, including aconfiguration associated with transmitting pilots using a dedicated setof resources (e.g., a radio resource control (RRC) dedicated state,etc.) or a configuration associated with transmitting pilots using acommon set of resources (e.g., an RRC common state, etc.). Whenoperating in the RRC dedicated state, the UE may select a dedicated setof resources for transmitting a pilot signal to a network. Whenoperating in the RRC common state, the UE may select a common set ofresources for transmitting a pilot signal to the network. In eithercase, a pilot signal transmitted by the UE may be received by one ormore network access devices, such as an AN, or a DU, or portionsthereof. Each receiving network access device may be configured toreceive and measure pilot signals transmitted on the common set ofresources, and also receive and measure pilot signals transmitted ondedicated sets of resources allocated to the UEs for which the networkaccess device is a member of a monitoring set of network access devicesfor the UE. One or more of the receiving network access devices, or a CUto which receiving network access device(s) transmit the measurements ofthe pilot signals, may use the measurements to identify serving cellsfor the UEs, or to initiate a change of serving cell for one or more ofthe UEs.

In 5G new radio (NR), aperiodic channel state information (CSI) reportsare triggered by a CSI report trigger transmitted from a base station toa user equipment. The CSI report trigger indicates to the UE the timingand allocated resources to perform CSI reporting. In some cases, whenthe CSI report are transmitted by the UE via a physical uplink sharedchannel (PUSCH), the CSI report trigger may be sent via and uplink (UL)grant containing a resource allocation (RA) information from which UE isaware of which resource is used to perform the CSI report. According toaspects, the CSI report may include a CSI-reference signal channelindicator (CRI), a rank indicator (RI), channel quality information(CQT), and a pre-coding matrix indicator (PMI). The PMI can be furthercategorized into wideband PMI (WB PMI) or subband PMI (SB PMI). For typeII linear combination codebook, the WB PMI includes rotation indication,beam indication, wideband amplitude indication and strongest beamindication; the SB PMI includes subband amplitude indicator and subbandphase indicator.

In some cases, the payload size of CRI, RI and CQI are fixed, while thePMI (especially the subband PMI) payload size may vary depending on thereported RI. From this aspect, the CSI reporting may be divided into twoor three parts, where the a first portion of the CSI feedback containsCRI/RI/CQI whose payload is fixed, while the second and third portionsof the CSI feedback contain PMI whose payload sizes depend on the firstportion (and where the third portion may also depend on the secondportion). Table 1, below, illustrates the different scenarios of whenCSI feedback may be partitioned into two or three portions and theinformation carried in each portion.

TABLE 1 1^(st) portion 2^(nd) portion 3^(rd) portion Case 1 CRI/RI/CQIPMI (WB/SB) (CQI for N/A (for 1^(st) 2^(nd) codeword may be codeword)included if applicable) Case 2 CRI/RI/CQI SB PMI (CQI for N/A (for1^(st) 2^(nd) codeword may be codeword)/ included if applicable) WB PMICase 3 CRI/RI/CQI WB PMI SB PMI (CQI for (for 1^(st) 2^(nd) codeword maycodeword) be included if applicable)

Example Subband CSI Omission for Type-H CSI

In the two-part CSI reporting scheme described above, certain parametersmay be included or may not be included (may be omitted) in a CSI report.As described above, the first part of the two-part scheme may containRI, CQI and an indication of the number of non-zero wideband amplitude(NZWA) coefficients per layer. Thus, while a fixed payload size may beused for the first part, the payload size of second part containingremaining CSI may vary.

Separately encoded parts of a CSI report carried on PUSCH also carryingUL-SCH (data) may have different transmission priority. For example, thefirst part (used to identify the number of information bits in part 2)may have a higher priority than the second part. Thus, the first partmay be included in a transmission in its entirety before part 2. In somecases, information bits and/or channel coded bits of part 2 may only bepartially transmitted. For example, CSI parameters corresponding tocertain subbands for part 2 may be omitted.

Aspects of the present disclosure provide techniques for determining howmany subbands should be reported (in the second part), as well as whichsubbands should be omitted.

FIG. 9 illustrates example operations 900 for wireless communications.Operations 900 may be performed, for example, by a UE for channel stateinformation reporting, in accordance with certain aspects of the presentdisclosure. Similar operations may be performed at the base station(e.g., gNB) side, for example, to determine the packet size and encodingused to process CSI reports from a UE.

Operations 900 begin, at 902, by determining, in a two-part channelstate information (CSI) reporting scheme, a first number M out of Nsubbands to use for feeding back CSI in a second CSI feedback part,wherein N represents a configured number of supported subbands forsubband precoding matrix indicator (PMI) reporting.

At 904, the UE decides, based on a rank indicator (RI) and a non-zerowideband amplitude (NZWA) per layer, which of the N subbands to omitfrom the M subbands. At 906, the UE may report CSI feedback for the Msubbands in the second CSI feedback part.

In other words, because the second packet (for part 2) payload sizedepends on both RI and non-zero wideband amplitude per layer (referredto as NAZ_(i) for the i-th layer), both RI and NAZ_(i) may be consideredas input for deciding which subband(s) to select for omission.

After deciding how many subbands to feedback (with the number ofsubbands to report referred to as M subbands), the actual subbandindex(es) to be fed back may need to be determined. In some cases, thesubband indexes to be omitted may be determined based CQI information inthe first packet (carrying the first part).

In some cases, the number of subbands M may be determined based on amapping rule or table, based on RI and non-zero wideband amplitude perlayer. For example, FIG. 10 illustrates an example mapping table (e.g.,for L=4 linear combined beams) that may be used by a UE, to determine Mbased on RI and NZWA. In this example, NZWA stands for the sum ofnon-zero wideband amplitudes per layer. For example, if 1^(st) layernon-zero amplitude is 2 and 2nd layer non-zero amplitude is 3, then NZWAwould be 5 (2+3). Given the M determined (e.g., from the table), Msubband PMI would then be included in the 2^(nd) packet. The mappingtable can be pre-defined or base station configurable.

Instead of a mapping table, a mapping rule may be used. For example, amapping rule based on NZWA and RI may be as follows:

${M = {{\left\lfloor {K*\frac{\alpha}{{NZWA} - 2}} \right\rfloor\mspace{14mu}{for}\mspace{14mu}{RI}} = 2}},{{{otherwise}\mspace{14mu} M} = K}$wherein, α could be based on parameters related to resource allocation.

In some cases, M may be chosen to ensure that Type-II subband payloadcan be carried in the CSI reporting. For example, given:Rank value v,v∈[1,2]wideband PMI payload size Q_(1,v), would be inclusive of all i₁ bits.Per subband PMI payload Q_(2,v), may be inclusive of all i₂ bits. Insome cases, a base station may configure subband size K. The maximumsupported payload size of the 2nd packet Q_(max), may be derived basedon, for example, a resource allocation (RA) for Type-II CSI (e.g.,resource allocation between 1st and 2nd packet).

In some cases, the per subband payload size Q_(2,v) may be determinedbased on RI and NZA_(i). M may be selected with a constraint, forexample, that:M*Q _(2,v) +Q _(1,v) ≤Q, _(max)This constraint may help ensure that a maximum supported number of Msubbands is fed back.

Actual subbands to omit from or include in M may be determined based onvarious factors. For example, omitted subbands may be determined basedon a decimation ratio and/or a priority pattern used to order subbandCSI (which may be defined in specification). In some cases, omittedsubbands may be determined based on the measured subband CQI included inpart 1 (in the 1 st packet).

In other words, the actual subband indexes (of the M subbands) may beselected according to the CQI in the 1^(st) packet. For example, in somecases, two subbands within N consecutive subbands may be selected forsubband PMI feedback. The two subbands may include one subbandassociated with the best CQI in the N subbands, and the other subbandmay be associated with the worst CQI in the N subbands. If M is an oddnumber, one subband (not associated with the best or worst CQI) may beselected from N*(M−1)/2+1˜K-th subband. In some cases, the number N ofconsecutive subbands may be determined based at least on K and M. Insome cases, a number of segmented subbands may be selected as:S=ceil(M/2).

In some cases, subbands corresponding to the best CQI associatedsubbands out of the subbands may be selected by a decimation pattern.For example, for M selected subbands for feedback, given that adecimation pattern may already define feedback subbands (M1), M2=M−M1subbands may be selected from the best CQI associated subbands out ofthe decimation selected beams.

For example, as illustrated in FIG. 1, with a total of N configuredsubbands, a decimation pattern may be used when M=N/2. If M>N/2, thenM−N/2 subbands which have best CQI in non-selected subbands may beincluded in part-2 PMI feedback. As illustrated in FIG. 11, this resultsin an additional 2 subbands being selected (in addition to the subbandsselected based on the decimation pattern). As illustrated, thedecimation pattern may result in the inclusion/omission of every othersubband. In other words, in some cases, the subband omission may beperformed to include only even subbands or odd subbands for the Type-IIfeedback, in an effort to ensure the wideband part is transmitted.

It should be noted that the techniques described above may equally applyto CSI reporting on both a long or short physical uplink control channel(PUCCH) or a physical uplink shared channel (PUSCH). Further, thetechniques described above may also equally apply to any of aperiodic,semi-persistent, or periodic CSI reporting.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

In some cases, rather than actually transmitting a frame, a device mayhave an interface to output a frame for transmission. For example, aprocessor may output a frame, via a bus interface, to an RF front endfor transmission. Similarly, rather than actually receiving a frame, adevice may have an interface to obtain a frame received from anotherdevice. For example, a processor may obtain (or receive) a frame, via abus interface, from an RF front end for transmission.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering. For example, operations 900 of FIG. 9 described abovemay be performed by one or more of transmit processor 464,controller/processor 480, or receive processor of the UE 120 of FIG. 4.

For example, means for transmitting, means for receiving, means fordetermining, means for performing, and/or means for re-transmitting maycomprise one or more processors or antennas at the BS 110 or UE 120,such as the transmit processor 420, controller/processor 440, receiveprocessor 438, or antennas 434 at the BS 110 and/or the transmitprocessor 464, controller/processor 480, receive processor 458, orantennas 452 at the UE 120.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userequipment 120 (see FIG. 1), a user interface (e.g., keypad, display,mouse, joystick, etc.) may also be connected to the bus. The bus mayalso link various other circuits such as timing sources, peripherals,voltage regulators, power management circuits, and the like, which arewell known in the art, and therefore, will not be described any further.The processor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer-readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, ROM (ReadOnly Memory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

The invention claimed is:
 1. A method for wireless communications,comprising: determining, in a two-part channel state information (CSI)reporting scheme, a first number M out of N subbands to use for feedingback CSI in a second CSI feedback part, wherein N represents aconfigured number of supported subbands for subband precoding matrixindicator (PMI) reporting; deciding, based on a rank indicator (RI) anda non-zero wideband amplitude (NZWA) per layer, which of the N subbandsto omit from the M subbands; and reporting CSI feedback for the Msubbands in the second CSI feedback part.
 2. The method of claim 1,wherein the determination of M is based on a mapping rule using the RIand NZWA.
 3. The method of claim 1, wherein the determination of M isbased on a lookup table accessed based on the RI and NZWA.
 4. The methodof claim 3, wherein the mapping table is configured by a base station.5. The method of claim 3, wherein the mapping table is associated withthe configured or allocated resource for CSI reporting.
 6. The method ofclaim 3, wherein the mapping table is generated differently depending onwhat resource is allocated for CSI feedback.
 7. The method of claim 1,wherein the determination of M is performed to ensure the CSI feedbackfor the M subbands will fit based on a payload size of the second CSIfeedback part.
 8. The method of claim 7, wherein M is selected based ona maximum supported value for the payload size.
 9. The method of claim1, wherein: a first subband associated with a best CQI in a set ofconsecutive subbands is included in the M subbands; and a second subbandassociated with a worst CQI in the set of consecutive subbands is alsoincluded in the M subbands.
 10. The method of claim 1, wherein: thesubbands to include in the M subbands is based on a decimation pattern.11. The method of claim 10, wherein: the subbands to include in the Msubbands is also based on a CQI associated with the subbands.
 12. Themethod of claim 10, wherein: the decimation pattern results in theinclusion of every other subband of a set of subbands.
 13. An apparatusfor wireless communications, comprising: means for determining, in atwo-part channel state information (CSI) reporting scheme, a firstnumber M out of N subbands to use for feeding back CSI in a second CSIfeedback part, wherein N represents a configured number of supportedsubbands for subband precoding matrix indicator (PMI) reporting; meansfor deciding, based on a rank indicator (RI) and a non-zero widebandamplitude (NZWA) per layer, which of the N subbands to omit from the Msubbands; and means for reporting CSI feedback for the M subbands in thesecond CSI feedback part.
 14. The apparatus of claim 13, wherein thedetermination of M is based on a mapping rule using the RI and NZWA. 15.The apparatus of claim 13, wherein the determination of M is based on alookup table accessed based on the RI and NZWA.
 16. The apparatus ofclaim 15, wherein the mapping table is configured by a base station. 17.The apparatus of claim 15, wherein the mapping table is associated withthe configured or allocated resource for CSI reporting.
 18. Theapparatus of claim 15, wherein the mapping table is generateddifferently depending on what resource is allocated for CSI feedback.19. The apparatus of claim 13, wherein the determination of M isperformed to ensure the CSI feedback for the M subbands will fit basedon a payload size of the second CSI feedback part.
 20. The apparatus ofclaim 19, wherein M is selected based on a maximum supported value forthe payload size.
 21. The apparatus of claim 13, wherein: a firstsubband associated with a best CQI in a set of consecutive subbands isincluded in the M subbands; and a second subband associated with a worstCQI in the set of consecutive subbands is also included in the Msubbands.
 22. The apparatus of claim 13, wherein: the subbands toinclude in the M subbands is based on a decimation pattern.
 23. Theapparatus of claim 22, wherein: the subbands to include in the Msubbands is also based on a CQI associated with the subbands.
 24. Theapparatus of claim 22, wherein: the decimation pattern results in theinclusion of every other subband of a set of subbands.
 25. An apparatusfor wireless communications, comprising: at least one processorconfigured to determine, in a two-part channel state information (CSI)reporting scheme, a first number M out of N subbands to use for feedingback CSI in a second CSI feedback part, wherein N represents aconfigured number of supported subbands for subband precoding matrixindicator (PMI) reporting and to decide, based on a rank indicator (RI)and a non-zero wideband amplitude (NZWA) per layer, which of the Nsubbands to omit from the M subbands; and a transmitter configured totransmit CSI feedback for the M subbands in the second CSI feedbackpart.
 26. A non-transitory computer readable medium having instructionsstored thereon for: determining, in a two-part channel state information(CSI) reporting scheme, a first number M out of N subbands to use forfeeding back CSI in a second CSI feedback part, wherein N represents aconfigured number of supported subbands for subband precoding matrixindicator (PMI) reporting; deciding, based on a rank indicator (RI) anda non-zero wideband amplitude (NZWA) per layer, which of the N subbandsto omit from the M subbands; and reporting CSI feedback for the Msubbands in the second CSI feedback part.